Motor vehicle seats are conventionally implemented as seats with a seat frame that is made of metal. This results, in particular in the case of motor vehicle seats having a foldable backrest, in a material-intensive implementation of the kinematics components of the folding mechanism, because the loads are transferred to the vehicle body via these kinematics components.
For motor vehicle seats having a foldable backrest there are solutions according to which the seat part is folded up in a forward direction and the backrest part is folded down into the space that becomes available in this manner. It is furthermore known to provide motor vehicle seats with foldable backrest parts and seat parts that can be lowered, wherein the backrest part can be folded onto the seat part in order to create essentially levels surfaces, in particular loading surfaces.
A motor vehicle seat of this type is for example disclosed in German Patent No. DE 198 41 363 C1. With this motor vehicle seat, the backrest can be folded onto the seat part, in order to create an additional loading surface adjacent to the luggage space wherein the additional loading surface is formed by the backside of the backrest. In order to have the additional loading surface extend essentially on the level of the floor of the luggage space, the seat must be as flat as possible when it is in its folded position. In order to achieve this, the seat part is lowered and is moved forward relative to the folding axis of the backrest when the backrest is folded forward. The seat part supports itself on the vehicle floor via a front swing arm (motion link) which is connected to the backrest via a rigid linkage. This linkage transfers the folding motion of the backrest to the swing arm such that the swing arm pivots forward and lowers the seat part as well as moves the seat part forward.
German Patent No. DE 199 62 424 C1 discloses a solution for a motor vehicle seat having a backrest and a seat part. The backrest is foldable about a folding axis. In the front region of the seat, the seat part is supported via a swing arm which can be swiveled in a longitudinal direction, wherein the folding motion of the backrest is transferred to the swing arm via the linkage such that the seat part is lowered by swiveling the swing arm when folding the backrest forward and is again raised when folding back the backrest.
A disadvantage of the conventional solutions is however that large portions of the seat part have to be engineered as a metal structure in order to meet the high demands with respect to stability. As a result, the seat is heavy. Furthermore, expensively structured kinematics components are required for these foldable seat assemblies because the loads are transferred into the vehicle body via these kinematics components. Therefore, a large number of precautions with respect to safety, such as a reinforced anchoring of the seat parts in the floor of the vehicle body are to be taken, in order to prevent that the seat breaks away in the case of an accident. In addition, the high weight has a disadvantageous effect on fuel consumption.